1. Field of the Invention
The present invention relates to an apparatus for recording imagery, characters and other kinds of information on recording media, particularly to an apparatus that performs recording while keeping its interior or the recording media at constant temperature or humidity.
2. Description of the Related Art
Recording heads such as thermal heads and laser heads can be used to record imagery, characters and other kinds of information. If the environment in such recording apparatus changes in terms of temperature or humidity, the performance of a constituent member such as the recording head or the recording sensitivity (hereunder referred to simply as xe2x80x9csensitivityxe2x80x9d) of the heat-sensitive material (hereunder referred to as the xe2x80x9csensitive materialxe2x80x9d) in the recording medium varies, substantially affecting the finished image.
A conventional recording apparatus comprises a rotating recording drum (hereunder referred to as xe2x80x9crecording drumxe2x80x9d) onto which is transported and fixed a recording medium (an image-receiving sheet and a plurality of sensitive materials such as toner sheets exemplified by standard K (black), C (cyan), M (magenta) and Y (yellow) toner sheets and sheets of specific colors such as gold and silver that are commonly used in the printing industry) and the recording medium is illuminated with laser light from a recording head to record imagery, characters and other kinds of information.
If the temperature in this conventional recording apparatus changes, it becomes difficult to ensure that uniform recording is done under identical conditions (in such terms as recording energy and time).
If the temperature in the recording apparatus decreases, the recording energy of the laser light issued from the recording head attenuates. Hence, the diameter of the beam spot projected from the recording head onto the recording medium becomes smaller than a specified value and, at the same time, the intensity of the laser light becomes insufficient to achieve satisfactory recording. As a result, the finished image becomes uneven and otherwise defective to cause serious effects, particularly on its quality if it is a color image. The same is true for the case where the temperature of the recording medium (hence, the sensitive material) decreases and in order to perform recording within the same duration of time, more recording energy is necessary, than when the temperature is high.
The sensitivity of the sensitive material also changes with the change in the humidity in the recording apparatus and it becomes difficult to ensure that uniform recording is done under identical conditions.
An optimum humidity of sensitive materials is generally about 70% and their sensitivity tends to decrease with decreasing humidity. Therefore, if the humidity within the recording apparatus is low, the humidity of the sensitive material also drops to lower its sensitivity and more recording energy is required than when the humidity is high.
In order to ensure that laser light having a specified value of recording energy is incident on the recording medium, one suffices to set the recording time for a larger value but this slows down the recording speed and cannot meet the demand for fast recording.
If the humidity in the recording apparatus is low, another problem occurs and that is the development of static charge in the areas where the recording medium contacts various constituent members of the apparatus. This static buildup is especially noticeable on the recording medium transport guide and transport jamming is a frequent problem. Static charge also affects the electronic components in the recording apparatus by, for example, causing failure in the flexible board.
On the other hand, since the dust brought into the recording apparatus causes definite adverse effects to it, it is preferable to keep the inside pressure of the recording machine positively by supplying the air from outside in order to overcome said problems, however, this makes it difficult to stabilize the temperature or humidity in the recording apparatus as discussed above.
To deal with these problems, temperature and humidity sensors are provided in the recording apparatus to detect the internal temperature and humidity and temperature- and humidity-corrected values for the recording conditions (such as laser modulation and scanning speeds) are calculated by software and the recording conditions are automatically adjusted on the basis of the calculated corrective values. However, the major problem of this prior art approach is that plenty of cost and time must be spent in developing the applicable software.
The present invention has been accomplished under these circumstances and has as an object providing an inexpensive recording apparatus that can control the internal temperature and humidity while keeping the positive pressure at the inside of the recording apparatus.
The stated object of the invention can be attained by the recording apparatus in this invention which comprises a medium fixing member for fixing a recording medium to its surface, a recording means for producing a record on said recording medium, and an air supply means for supplying air into the apparatus to build up positive pressure in its interior, characterized in that at least one member of the group consisting of a dehumidifying means, a humidifying means, a heating means and a cooling means is contained within said recording apparatus so that either temperature or humidity or both are held constant in said recording apparatus.
The recording apparatus in the second aspect of this invention is characterized in that at least one member of the group consisting of a dehumidifying means, a humidifying means, a heating means and a cooling means is located at the upstream of the air supply port of said air supply means so that either temperature or humidity or both of them are held constant in said recording apparatus.
The recording apparatus in the third aspect of this invention is characterized in that said humidifying means is located in the feed path of said recording medium.
The recording apparatus in the fourth aspect of this invention is characterized by further including a humidifying chamber and a humidifying air supply means for supplying air to said humidifying chamber, said humidifying means performing its function by a water-retaining material that is imbibed with water and which is located within said humidifying chamber or between said humidifying air supply means and said humidifying chamber.
The recording apparatus in the fifth aspect of this invention is characterized in that said humidifying means performs its function by a water-retaining roller that is brought into contact with or proximity to the supply path of the recording medium.
The recording apparatus in the sixth aspect of this invention is characterized by further including a temperature correcting means for correcting the recording energy of said recording means.
The recording apparatus in the seventh aspect of this invention is characterized by further including a temperature control means for controlling the temperature of said recording drum to optimize the temperature of said recording medium fixed on said recording drum.
In the recording apparatus in another aspect, a recording medium is fixed to the surface of a medium fixing member and a record is produced on the recording medium by a recording means, with air being supplied into the apparatus from outside of it by an air supply means to build up positive pressure in its interior. In the recording apparatus of claim 2, at least one member of the group consisting of a dehumidifying means, a humidifying means, a heating means and a cooling means is provided at the air supply port of the air supply means so that either temperature or humidity or both are held constant in the recording apparatus.
Thus, in the recording apparatus, at least one member of the group consisting of a dehumidifying means, a humidifying means, a heating means and a cooling means is provided at the air supply port of the air supply means so that either temperature or humidity or both are held constant (at an optimum value) in the recording apparatus to ensure that there will be no change of the temperature and humidity in the recording apparatus that would otherwise deteriorate the performance of its constituent members or reduce the sensitivity of the sensitive material in the recording medium. As a result, the recording apparatus can perform recording without waste of recording energy while preventing unevenness in the finished image. In the absence of humidity changes in its interior, the recording apparatus is free from the development of static charge in the areas of contact between the recording medium and the constituent members and from the subsequent transport jamming and failure in electronic components.
In the recording apparatus recited in in further aspect, a recording medium is fixed to the surface of a medium fixing member and a record is produced on the recording medium by a recording means, with air being supplied into the apparatus by an air supply means to build up positive pressure in its interior. In the recording apparatus of claim 3, a humidifying means is located in the feed path of the recording medium in order to keep its humidity constant.
Thus, in the recording apparatus, a humidifying means is provided in the feed path of the recording medium to humidify it so that its water content is kept at an optimum level. This ensures against the drop in the sensitivity of those sensitive materials which are particularly sensitive to humidity changes. As a result, the recording apparatus can perform recording without waste of recording energy while preventing unevenness in the finished image.
Take, for example, the humidifying means; it comprises a humidifying chamber and a humidifying air supply means and performs its function by a water-retaining material that is imbibed with water and which is located within the humidifying chamber or between the humidifying air supply means and the humidifying chamber. As a result, the water content of the recording medium is held at an optimum level.
Alternatively, the humidifying means performs its function by a water-retaining roller that is brought into contact with or proximity to the feed path of the recording medium. This is also effective in holding the water content of the recording medium at an optimum level.